Abstract: The conventional method of estimating joint moments needs kinematic data measured with a 3D optical motion measurement system and ground reaction forces measured with force plate. However, the conventional method is limited generally to laboratory use because of the required measurement systems. Therefore, we proposed a convenient method to estimate joint moments from measurements only with inertial sensors for application to clinical evaluation of motor function of paralyzed and elderly subjects. In this paper, multi-link modeling of the trunk was examined for reliable estimation of joint moments only from measured data with inertial sensors attached on the body. Body segment parameters (segment length and mass, center of mass location and moments of inertia) were calculated from anthropometric data. Experimental test with 3 healthy subjects showed that segmented trunk model estimated joint moments better than a rigid trunk model for squat and sit-to-stand movements. The estimation results were not different largely between the 5-link model that modeled the trunk by 3 segments and the 4-link model that modeled the trunk by 2 segments. However, trunk modeling for 4-link model was suggested to be appropriate when the upper and the middle trunk segments of the 5-link model were modeled as one segment.(More)

The conventional method of estimating joint moments needs kinematic data measured with a 3D optical motion measurement system and ground reaction forces measured with force plate. However, the conventional method is limited generally to laboratory use because of the required measurement systems. Therefore, we proposed a convenient method to estimate joint moments from measurements only with inertial sensors for application to clinical evaluation of motor function of paralyzed and elderly subjects. In this paper, multi-link modeling of the trunk was examined for reliable estimation of joint moments only from measured data with inertial sensors attached on the body. Body segment parameters (segment length and mass, center of mass location and moments of inertia) were calculated from anthropometric data. Experimental test with 3 healthy subjects showed that segmented trunk model estimated joint moments better than a rigid trunk model for squat and sit-to-stand movements. The estimation results were not different largely between the 5-link model that modeled the trunk by 3 segments and the 4-link model that modeled the trunk by 2 segments. However, trunk modeling for 4-link model was suggested to be appropriate when the upper and the middle trunk segments of the 5-link model were modeled as one segment.